You're too busy to seal your double window security envelopes the old-fashioned way. Thanks to Redi-Seal closures, these double window security envelopes keep the contents secure and require no moisture to stick. Redi-Seal envelopes are easy to secure. Simply raise the lower flap and press to seal. Double-window security envelopes contain 2 poly windows - one for the return address and one for the mailing address. Quality Park double window envelopes feature a unique double flap design keeps the gum from sticking before use. Security envelopes feature a tinted inside for privacy and confidentiality. Made of crisp 24-lb white wove for a substantial feel. #8 envelopes are made of crisp 24-lb white wove for a substantial feel. Quality Park(R) Redi-Seal(TM) Double-Window Security Envelopes, #8 5/8 (3 5/8in. x 8 5/8in.), White, Box Of 500 is one of many Business Envelopes available through Office Depot. Made by Quality Park.